A5030258030- Planetary Science and Exploration
- Astro and Planetary Science
- Seismic Waves and Analysis
- Methane Hydrates and Related Phenomena
- earthquake and tectonic studies
- Cryospheric studies and observations
- Geophysics and Sensor Technology
- High-pressure geophysics and materials
- Seismology and Earthquake Studies
- Seismic Imaging and Inversion Techniques
- Earthquake Detection and Analysis
- Space Science and Extraterrestrial Life
- Geology and Paleoclimatology Research
- Space Exploration and Technology
- Geological and Geochemical Analysis
- Ionosphere and magnetosphere dynamics
- Reservoir Engineering and Simulation Methods
- Spacecraft Design and Technology
- Landslides and related hazards
- Stellar, planetary, and galactic studies
- Climate change and permafrost
- Marine and environmental studies
- Spacecraft and Cryogenic Technologies
- Geomagnetism and Paleomagnetism Studies
- Winter Sports Injuries and Performance
University of Arizona
2024
Jet Propulsion Laboratory
2018-2023
University of Maryland, College Park
2017-2022
Charles University
2021
Goddard Space Flight Center
2021
University of Illinois Chicago
2021
The University of Texas at Austin
2021
California Institute of Technology
2021
University of Georgia
2021
Boston University
2013
Clues to a planet's geologic history are contained in its interior structure, particularly core. We detected reflections of seismic waves from the core-mantle boundary Mars using InSight data and inverted these together with geodetic constrain radius liquid metal core 1830 ± 40 kilometers. The large implies martian mantle mineralogically similar terrestrial upper transition zone but differing Earth by not having bridgmanite-dominated lower mantle. inferred mean density 5.7 6.3 grams per...
Several seismic experiments were deployed on the Moon by astronauts during Apollo missions. The began in 1969 with 11, and continued 12, 14, 15, 16 17. Instruments at 17 remained operational until final transmission 1977. These remarkable provide a valuable resource. Now is good time to review this resource, since InSight mission returning data from Mars, missions Europa are development different space agencies. We present an overview of available four sets Moon: Passive Seismic Experiments,...
ABSTRACT The mutual gravitational interaction of binary asteroids, which make up approximately 15 per cent the near-Earth asteroid (NEA) population, provides a continuous tidal force, creating ground motion. We explore potential kilometre-sized asteroids as targets for seismological studies their interior structure. use numerical model wherein each body is constructed discrete particles interacting via gravity and contact forces. system's orbital properties are modelled based on those...
Abstract Observations of the ionosphere Mars have now reached a sufficient number to begin discussions on how best create an empirically based model its global morphology. Here we use nearly 113,000 values maximum electron density ( N max ) obtained from 2005 2012 by Advanced Radar for Subsurface and Ionospheric Sounding board Express satellite. At altitude peak density, photochemical processes dominate over dynamical effects, thus can be organized using three basic parameters: solar flux,...
Before deploying to the surface of Mars, short-period (SP) seismometer InSight mission operated on deck for a total 48 hours. This dataset can be used understand how deck-mounted seismometers in future landed missions Europa, and other planetary bodies. While operating deck, SP showed signals comparable Viking-2 near 3 Hz where sensitivity Viking instrument peaked. Wind similar patterns instrument, although amplitudes were ~80% larger given wind velocity. However, during low evening hours...
Abstract Geophysics-focused missions and improved geophysical data sets are critical for the future exploration of icy ocean worlds. Of particular interest is Galilean moon, Europa, Saturnian moons, Titan Enceladus. These bodies likely have geologically active surfaces may harbor habitable subsurface environments. Placing any candidate signatures life in context requires further knowledge interior these While been mapped, their interiors remain poorly understood. Geophysical approaches such...
Abstract We investigate the effects of methane clathrates on Titan’s thermal and seismic structure. The Dragonfly mission is planned to arrive at Titan in 2033 with a payload that includes package. instruments are tasked recording events recovering internal Here, we explore whether differences profiles between pure water ice shell an clathrate lid could be detectable instrumentation. Due their lower conductivity, reduce conductive thickness thus altering profile. velocities ice, coupled...
Abstract Titan’s impact craters are hundreds of meters shallower than expected, compared to similar-sized on Ganymede. Only 90 crater candidates have been identified, the majority which low certainty an origin. Many processes suggested shallow, modify, and remove craters, including fluvial erosion by liquid from rainfall, aeolian sand infill, topographic relaxation induced insulating infill. Here we propose additional mechanism: due methane clathrate crustal layer in upper ice shell. We use...
Abstract Spectral characterization of near-Earth asteroids (NEAs) has revealed a continuum space-weathered states for the surfaces S-complex NEAs, with Q-class an subclass, most closely matching unweathered ordinary chondrite meteorites. Dynamical calculations orbital evolution NEAs that tend to have close encounters terrestrial planets, suggesting planetary tides may play role in refreshing NEA surfaces. However, exact physical mechanism(s) drive resurfacing through tidal and encounter...
Abstract The Seismometer to Investigate Ice and Ocean Structure (SIIOS) is a NASA-funded analog mission program test flight-candidate instrumentation on icy-ocean world sites. In September 2017, an SIIOS experiment was deployed Gulkana Glacier. included Nanometrics Trillium 120 s Posthole seismometer, four Compact (TC) seismometers, Mark Products L28 geophones, five each of Silicon Audio (SiA) 203P-15 203P-60 seismometers. SiA sensors served as our instruments. arranged in small (<2...
Abstract Detecting a seismic event from Europa's silicate interior would provide information about the geologic and tectonic setting of moon's rocky interior. However, subsurface ocean will attenuate signal, possibly preventing waveforms being detected by surface seismometer. Here, we investigate minimum magnitude detectable originating We analyze likely signal‐to‐noise ratios compare predicted signal strengths to current instrument sensitivities. show that M w ≥ 3.5 be sufficient overcome...
Abstract In anticipation of future spacecraft missions to icy ocean worlds, the Seismometer Investigate Ice and Ocean Structure (SIIOS) was funded by National Aeronautics Space Administration, prepare for seismologic investigations these worlds. During summer 2018, SIIOS team deployed a seismic experiment on Greenland ice sheet situated, approximately, 80 km north Qaanaaq, Greenland. The seismometers included one Trillium 120 s Posthole (TPH) broadband seismometer, 13 Silicon Audio...
Whitepaper #098 submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032. Topics: interior evolution volcanism; Mercury and/or Moon; solar system formation, dynamics processes, chronology
A seismic investigation on Saturn's moon Enceladus could determine the thickness of ice shell, along with variations from mean thickness, by recovering phase and group velocities, through frequency content surface waves. Here, we model shell uniform thicknesses 5 km, 20 40 as well topography ranging 5-40 km. We investigate several approaches for thickness. show that wave dispersions be used to Flexural waves in only occur if is thinner than a critical value < Rayleigh dominate thicker...
&lt;p&gt;&lt;strong&gt;Introduction:&lt;/strong&gt;&amp;#160; A plethora of geophysical, geo-chemical, and geodynamical observations indicate that the terrestrial planets have differentiated into silicate crusts mantles surround a dense core. The latter consists primarily Fe some lighter alloying elements (e.g., S, Si, C, O, H). There is strong evidence from measurements tidal deformation planet core Mars presently liquid.&lt;/p&gt;&lt;p&gt;The...
Abstract The ionosphere's response to geomagnetic storms has been studied since the earliest days of terrestrial space physics. In terms temporal coverage, largest data sets used extensively have from global network ionosondes. Many previous investigations examined behavior F layer's maximum electron density ( N max )—often contrasting difference seen between that occur during solar years versus those minimum years. We report on first attempt study systematically patterns ionospheric...
Abstract. In this study, we report the results of an active-source seismology and ground-penetrating radar survey performed in northwestern Greenland at a site where presence subglacial lake beneath accumulation area has previously been proposed. Both seismic show flat reflector approximately 830–845 m below surface, with reflection coefficient −0.43 ± 0.17, which is consistent acoustic impedance contrast between layer water glacial ice. Additionally, data observe intermittent bottom...
Abstract Future missions carrying seismometer payloads to icy ocean worlds will measure global and local seismicity determine where the ice shell is seismically active. We use two locations, a active site on Gulkana Glacier, Alaska, more quiet northwestern Greenland Ice Sheet as geophysical analogs. compare performance of single‐station against small‐aperture seismic array detect both high (>1 Hz) low (<0.1 frequency events at each site. created catalogs (HF) (LF) location using an...
Spectral characterization of near-Earth asteroids (NEAs) has revealed a continuum space-weathered states for the surfaces S-complex NEAs, with Q-class an subclass, most closely matching un-weathered ordinary chondrite meteorites. Dynamical calculations orbital evolution NEAs that tend to have close encounters terrestrial planets, suggesting planetary tides may play role in refreshing NEA surfaces. However, exact physical mechanism(s) drive resurfacing through tidal and encounter distance at...
Abstract Previous 1‐D spherically symmetric seismic modeling studies have shown that in the presence of a clathrate lid on Titan significant thermal profile differences result, particularly comparison to pure water ice shell. In turn, these would lead notable changes waveform amplitudes and phase arrival times. this study we investigate feasibility using surface waves dispersion explore structure Titan's We ability measure observe frequency‐dependent signals (0.003–0.100 Hz) their utility...